Exhaust brake on Cummins 350 ISC

[sancat_sancat@yahoo.com]

I have a 40-foot 2003 American Tradition with a 350 Cummins ISC with 69,000 miles. Today when traveling over the Cascade mountains, when I would use the exhaust brake when coming down the many steep grades I would switch the exhaust brake off at the bottom and step on the accelerator pedal the engine would feel like it was running out of fuel for about 20 or 30 seconds. Then, it would run fine. One time it sent a large white smoke cloud out the exhaust. It ran fine going up the mountain and on the flat. It only sputtered after coming down with the exhaust brake. Has anybody had this problem?

[tbutler]

Welcome sancat11,

Here, Smoking Engine, is a link to a previous discussion of a smoking/performance problem with a Cummins 400 ISL. While you have a different engine and the circumstances are somewhat different, you might take the advice in the that discussion. Contacting Cummins with your engine serial number might give you some help.

[wolfe10]

Good advice from Tom with your ISL.

You also need to verify that the exhaust brake is not seizing up-- that it freely snaps open and snaps closed.

Do you lube your exhaust brake? If a PacBrake: http://www.pacbrake.com/index.php?page=maintenance

Sitting for long periods of time also contributes to seizing up.

Brett

[garykd]

Hi sancat11,

Best I know, the Cummins ISC does not have an exhaust brake. It has an engine brake.

An Engine brake is a compression release brake. It works by opening the exhaust valves at the top of the compression stroke, releasing the compressed air in; then immediately closing the valves to create an extreme vacuum in the cylinder and providing immense amounts of braking force.

An exhaust brake works by causing a restriction in the exhaust much like the intake throttle causes in a gasoline engine. Nearly all of these brakes are butterfly valves mounted downstream of the turbocharger.

Before doing anything, try:

1. not turning off the engine brake. Just before the bottom of the decent, start to feather the accelerator to remove the engine brake from holding the coach back. Then at the bottom of the hill gradually step on the accelerator to maintain the proper speed.

2. If you do not expect to use the engine brake again for some time, then turn it off. If you expect to use it again, shortly, leave it on for the next decent.

[wolfe10]

Hi sancat11,

Best I know, the Cummins ISC does not have an exhaust brake. It has an engine brake.

NO, the ISL (8.9 liter) is the smallest Cummins that can be ordered with a compression brake, and many of them are exhaust brake equipped.

All C engines (8.3 liter) are exhaust brake only.

Brett

[garykd]

Hi Brett,

You are correct. My post has the definition correct, but my engine has an exhaust brake. My selective memory is getting smaller every day.

[sanmel2002@yahoo.com]

Sancat11,

I have a 40' 01 American Dream with ISC350 and Pac brake. It sounds like your PacBrake is freezing up, probably because it has not been adequately lubed. I had a problem about 4 years ago where the PacBrake locked up and engine lost power. Finally freed it up and went to Cummins/Spartan dealer and had it replaced. Since then, I have used the high temp lube sold by PacBrake every 6 months or so and never had another problem. Suggest you call PacBrake, obtain their hi temp lube and verify with them condition of brake. Thereafter make sure that brake is lubed regularly. Good luck.

Mel Silverstein

[russell@rfcellutions.com]

Frequent lubrication and frequent use is key to keeping these in order. Also down shift before starting down a hill. If you come up in 6th and the hill is 4-5 degrees maybe you want gown down in 5th or 4th. The closer you are to the transmission shift points the more breaking you will get. Going down the west side of the tunnel West of Denver 4th or 3rd works well to keep the coach speed between 35 and 40 MPH. I switch on when the speed comes up to 40 and off when it drops to 35. In this way I do not break just use the PAC brake.

[k7jv@arrl.net]

We had an exhaust brake on our last Cummins powered motorhome, and we had a similar problem. For us, it turned out that the electrically operated solenoid valve body would stick. It ports air to either the close side or the open side of the exhaust brake valve actuator, which was dual-acting. The solenoid body was an aluminum block perhaps 1 1/4" x 1/2" x 3", and had a two-conductor cable (the actuating power), and three air lines, and had the solenoid mounted on one end. One air line was the air supply, one was to the close side of the actuator, and one was to the open side of the actuator. There was also a small copper colored air filter on the discharge port of the valve body.

That valve body can be disassembled and cleaned, and lubricated. I was never happy with the long term success of cleaning and lubricating the valve, but that did solve the problem, for a time, each time. It wasn't terribly difficult to do, and probably took perhaps 20 minutes to do the whole job. And, replacement valve parts can be ordered from PacBrake, and can be found on-line.

On our coach, the solenoid valve was located in the engine compartment, and was actually mounted on a light weight metal bracket, located on the left (viewed from the bedroom, looking towards the back of the coach), back and top of the engine. I hope this helps.

[Crusingator]

I have been waiting to see if an owner of any of the Spartan chassis coaches with the EPA07 engine weres going to jump in. The Cummins ISC is available with a two speed compression brake. I know several friends with Tiffin Phaetons on Spartan chassis with them.

Research Jacobs Vehicle Systems, JAKE BRAKE MODELS 490/490A

Application Information

For the most accurate application information, refer to the Cummins Application Guide (Jacobs P/N 20994 Bulletin 3401804), available from your Cummins Distributor or online at www.jakebrake.com.

[wolfe10]

I have been waiting to see if an owner of any of the Spartan chassis coaches with the EPA07 engine weres going to jump in. The Cummins ISC is available with a two speed compression brake. I know several friends with Tiffin Phaetons on Spartan chassis with them.

Research Jacobs Vehicle Systems, JAKE BRAKE MODELS 490/490A

Application Information

For the most accurate application information, refer to the Cummins Application Guide (Jacobs P/N 20994 Bulletin 3401804), available from your Cummins Distributor or online at www.jakebrake.com.

Yes, for the 2007 and newer Cummins ISC, there is an engine compression brake available. BUT, NOT for any Cummins C engine built before 1/1/07.

It certainly would not be available for the OP's 2003 model.

Brett

[hermanmullins]

Welcome sancat11,

Here, Smoking Engine, is a link to a previous discussion of a smoking/performance problem with a Cummins 400 ISL. While you have a different engine and the circumstances are somewhat different, you might take the advice in the that discussion. Contacting Cummins with your engine serial number might give you some help.

Tom, the 'Smoking Engine' was my post. If you promise not to tell Brett, I will tell you what my problem was. My 400 ISL has the Jake Brake.

Now for the story. I had installed a new fan on my dash and looked for a curcit that came on and off with the egnition switch. On a trip back home we came to a down grade and I stepped on the Jake Brake. which slowed the coach down. That was when I noticed the fan quit. When I let off the Jake Brake the fan came back on. [Jake brake on fan off, jake Brake off fan on]. I had a stop light and when I came to a stop the engine went into rough idle, no power with lots and lots of smoke. I got through the intersection and on to the side of the road. This was the same problem I had before. "What the H- did I do but reach up and turn the fan off. WALII the engine begins to odle smoothly and the smoking stopped. What ever hot wire I connected the fan to was also connected to the Jake Brake. Needless to say I have removed the fan wire and moved it to the elec. panel and put in a inline fuse.

No more problems. [but Tom please don't tell Brett]

[wolfe10]

Tom, the 'Smoking Engine' was my post. If you promise not to tell Brett, I will tell you what my problem was. My 400 ISL has the Jake Brake.

Now for the story. I had installed a new fan on my dash and looked for a curcit that came on and off with the egnition switch. On a trip back home we came to a down grade and I stepped on the Jake Brake. which slowed the coach down. That was when I noticed the fan quit. When I let off the Jake Brake the fan came back on. [Jake brake on fan off, jake Brake off fan on]. I had a stop light and when I came to a stop the engine went into rough idle, no power with lots and lots of smoke. I got through the intersection and on to the side of the road. This was the same problem I had before. "What the H- did I do but reach up and turn the fan off. WALII the engine begins to odle smoothly and the smoking stopped. What ever hot wire I connected the fan to was also connected to the Jake Brake. Needless to say I have removed the fan wire and moved it to the elec. panel and put in a inline fuse.

No more problems. [but Tom please don't tell Brett]

Now, Herman, connecting to an engine control circuit to power a fan will only get you 5 minutes in time out-- no big deal. You will be out in plenty of time to join everyone for lunch.

But, it does bring up a good point. With today's electronic engines and transmissions (both gas and diesel), one needs to be very careful with modifications, particularly with things like fans that can produce RF Interference as well as being an electrical load.

Brett

[hermanmullins]

Now, Herman, connecting to an engine control circuit to power a fan will only get you 5 minutes in time out-- no big deal. You will be out in plenty of time to join everyone for lunch.

But, it does bring up a good point. With today's electronic engines and transmissions (both gas and diesel), one needs to be very careful with modifications, particularly with things like fans that can produce RF Interference as well as being an electrical load.

Brett

Brett, Tom wasn't supose to tell you of my fupa.

[PS, now I know.]